Mouthpeice intended for a device used to assess the sensitivity of the pharynx and a device comprising same

ABSTRACT

To assess the sensitivity of a subject&#39;s pharynx, an open mouthpiece ( 1 ) fitted with a thin guide tube ( 2 ), having an articulated end ( 4 ), is inserted into the subject&#39;s mouth. A pipe ( 9 ) is inserted into the guide tube, under visual observation through the mouthpiece, until it touches the subject&#39;s palate. The position on a measurement scale ( 11 ) provided on the pipe facing a second end of the guide tube is noted, and the pipe is withdrawn over a preset distance, for example 1 cm, and fixed in this position onto the guide tube. A variable gas flow is injected into the pipe and reaches the pharyngeal mucous situated facing the pipe. The sensitivity of the subject&#39;s pharynx, measured by the threshold of sense perception, is determined by the lowest flow value perceived by the subject.

BACKGROUND OF THE INVENTION

[0001] The invention relates to a mouthpiece intended for a devicedesigned for assessing the sensitivity of the pharynx, and a devicecomprising same.

STATE OF THE TECHNIQUE

[0002] Few means exist at present to evaluate the sensitivity of thepharynx. However this evaluation is desirable in a certain number ofpathologies involving a malfunctioning of the pharynx, such as sleepapnea. Processes based on mechanical or electrical stimulation of thepharynx are accompanied by undesirable effects, such as inducing anauseous reflex, which limits the use thereof on a certain number ofsubjects.

[0003] The document WO-A-9,611,627 describes a device using stimulationof the pharynx by a sequence of pulsed air jets of pre-determinedduration, for example 50 ms, and of variable pressure, for examplebetween 0 and 10 mm of mercury in steps of 7.5×10⁻² mm of mercury. Thepulsed air jets are injected into the zone to be tested via a flexibletube of small diameter fixed to a fibroscope which is inserted into thenose of the patient to be examined, like those commonly used forobservation of the pharynx. The pipe conveying the air may be integratedin the fibroscope. The patient's response to the stimulus constituted bya pulsed air jet can correspond either to an indication given by thepatient or to observation of a reflex such as closing of the vocalchords observed by means of a fibroscope. Such a device is complex andcostly. It does in fact require a sophisticated technical set-up andspecialised skills from the user, which limits the number of subjectsable to be examined.

OBJECT OF THE INVENTION

[0004] The object of the invention is to overcome the drawbacks of knownsystems and to provide simple, inexpensive means of evaluating thesensitivity of the pharynx, limiting the undesirable effects on thepatient.

[0005] According to the invention, this object is achieved by amouthpiece to be used for evaluating the sensitivity of the pharynx thatcomprises an open mouthpiece having internal dimensions enabling visualinspection of the pharynx, a thin guide tube fixed along an internalwall of the mouthpiece and comprising a first articulated end salientfrom a first end of the mouthpiece, a pipe designed to be connected viaa first end to a compressed gas source and inserted via a second endinside the guide tube, and means for fixing the pipe in the guide tubein a pre-determined position.

[0006] The invention also relates to a device for evaluating thesensitivity of the pharynx, comprising a compressed gas source, meansfor blowing gas in the direction of the pharynx, a mouthpiece accordingto the invention and means for measuring the flow rate of a gas injectedinto a first end of the pipe.

[0007] A process for using a device according to the invention forevaluating the sensitivity of the pharynx comprises insertion of thefirst end of the mouthpiece into the subject's mouth, insertion of thesecond end of the pipe into the guide tube, checked visually through themouthpiece, until it touches the subject's palate, withdrawal of thepipe over a preset distance measured by graduations of the pipe,connection of the first end of the pipe to the compressed air source,injection of a variable air flow of preset flowrate into the pipe, thesensitivity of the pharynx being determined according to the flow valuesfor which the subject is able to feel the air flow.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Other advantages and features will become more clearly apparentfrom the following description of particular embodiments of theinvention given as non-restrictive examples only and represented in theaccompanying drawings in which:

[0009]FIG. 1 represents, in cross-section, a particular embodiment of amouthpiece according to the invention.

[0010]FIG. 2 represents the mouthpiece according to FIG. 1 in positionin a patient's mouth.

[0011]FIG. 3 represents a particular embodiment of a device according tothe invention.

DESCRIPTION OF PARTICULAR EMBODIMENTS

[0012] The mouthpiece represented in FIGS. 1 and 2 comprises an openmouthpiece 1 forming the body of the mouthpiece and preferably formed bya cylinder open at both ends, a few centimetres in diameter and a fewcentimetres in length. As an example, the cylinder can be 2 to 3 cm indiameter and 4 cm in length. It can be narrower to enable evaluation ofthe sensitivity of the pharynx of subjects, like children, whose mouthopening is narrow. Its length can be reduced to make it easier to keepit in the subject's mouth.

[0013] A thin guide tube 2 is fixed, for example by glue 3, along aninternal wall of the mouthpiece 1. The guide tube 2 is preferably formedby a blow-pipe, i.e. a small tube or straw, made of plastic material,generally used to suck a liquid. It has a diameter of a few millimetres,for example 4 to 5 mm, and extends a few centimetres, for example 3 cm,beyond each end of the mouthpiece. It is moreover articulated at a firstend 4 designed to be inserted into the subject's buccal cavity 5. Thisarticulation enables the end 4 of the guide tube 2 and the pipe 9described above to be positioned facing the membranous palate 18,between the bony palate 19 and the tongue 20, whatever the morphology ofthe oral cavity of the subject examined. In FIG. 2, a second position ofthe end 4 is illustrated in a broken line.

[0014] The mouthpiece 1 comprises an external holding rim 6 at a firstend designed to be inserted into a subject's mouth. A rib 7,substantially parallel to the holding rim 6, can be provided to make iteasier for the subject to keep the mouthpiece in his mouth. The rib 7preferably comprises an inclined face 8 on the side opposite the holdingrim 6.

[0015] The mouthpiece also comprises a pipe 9 designed to be connectedvia a first end to a compressed gas source and inserted via a second endinto the guide tube 2. The diameter of the pipe 9 is slightly smallerthan that of the guide tube 2 so as to be able to be easily insertedinto the latter. In a preferred embodiment, the diameter of the pipe 9is about 2 mm. The pipe 9 can for example be formed by an oxygen probeof conventional type made of flexible plastic material, comprising aconnecting element 10 at its first end for connection to the compressedgas source.

[0016] The pipe 9 comprises a measurement scale 11 designed to cooperatewith the second end of the guide tube 2, opposite its articulated firstend 4, and located outside the subject's buccal cavity 5 during use ofthe mouthpiece.

[0017] To evaluate the sensitivity of a subject's pharynx, themouthpiece 1 equipped with the guide tube 2, the articulated end 4whereof is directed in a suitable manner, is inserted into the subject'smouth via its first end comprising the holding rim 6. As represented inFIG. 2, the teeth 12 of the subject's upper and lower maxillaries areplaced behind the holding rim 6, between the holding rim and the rib 7,thus securing the mouthpiece 1 in the subject's mouth. The subject'slips 13 then take the same shape as that of the mouthpiece 1 and restnotably on the inclined face 8 of the rib 7. Only a small part of themouthpiece 1 is then in the subject's mouth, most of the mouthpiece 1,from the rib 7 to the second end of the mouthpiece 1, opposite theholding rim 6, extending outside.

[0018] The internal dimensions of the mouthpiece are such as to enablevisual inspection of the pharynx, in spite of the presence of the guidetube 2. The second end of the pipe 9 is inserted into the guide tube 2,under visual observation through the mouthpiece 1, until it touches thesubject's palate. The position on the measurement scale facing thesecond end of the guide tube is noted, and the pipe is then withdrawnover a preset distance, for example 1 cm. There is then no longer anycontact between the end of the pipe and the palate, but the distancebetween this end and the palate is still the same whatever themorphology of the palate of the subject examined. A clamp 14, or in theabsence thereof, sticky tape, is then used to fix the pipe 9 in thisposition with respect to the guide tube 2.

[0019] The pipe 9 is connected, possibly by means of a connection oflarger diameter and a wall socket, to a compressed gas source,preferably to a compressed air bottle or an oxygen bottle. A flowmeter15 (FIG. 3) enables the gas flow injected into the pipe 9 to be adjustedand measured accurately. A variable gas flow of preset flow rate isinjected into the pipe 9 and reaches the pharyngeal mucous of the palatesituated facing the pipe 9. To give the subject being examined a firstindication of the sensation he should feel, a high flow, for example 2L/min, is administered and is then progressively reduced in steps,asking the subject at each step if he still perceives the sensation. Heindicates, by means of the means of indicating agreed on before theexamination, whether he perceives the gas flow or not. The lowest flowstill perceived corresponds to the threshold of sense perception. Tovalidate the measurement, the procedure is repeated at least two moretimes and the different values obtained are then averaged. Theperception threshold is then measured by administering increasing flowsper step, starting from a nil flow. At each step the subject is asked ifhe perceives the flow. The lowest value of the gas flow perceivedcorresponds to the threshold of sense perception. Measurement isrepeated at least twice and the different values obtained are thenaveraged. Asking at each step whether the subject perceives a sensationmay potentially influence the answer. Another way of proceeding istherefore to ask the subject to indicate by a physical gesture, or byany other means, when the pharyngeal sensation disappears or appears.During the experiment, the subject is requested to close his eyes andheadphones may be fitted on his ears to facilitate concentration onperception of the flow at the level of the pharyngeal mucous. Theheadphones also prevent the subject's responses from being influenced bythe sound of modifications of the gas flow. Finally, in the course ofthe examination, the subject has to breathe through his nose to preventany interference between the gas flow administered on the mucous and theair breathed in. For this purpose, the mouthpiece may be blocked up atits second end, in particular by means of a ball of cotton-wool 17.

[0020] This device is very simple and inexpensive. The graduations ofthe pipe 9 suffice, in combination with a temporary prior contact of thesecond end of the pipe with the palate, under visual observation, toensure a standard positioning for all subjects. The articulation of thefirst end of the guide tube 2 moreover enables the device to be adaptedto the morphology of the palate of a large number of subjects. Only therate of the gas flow is taken into account, neither its pressure nor theinjection time having to be taken into account. Such a device can easilybe used by any doctor having a compressed air or oxygen source at hisdisposal.

[0021] To avoid drying of the pharyngeal mucous in the course of theexamination, the device can comprise a humidifier 16 (FIG. 3), fittedbetween the gas source and the inlet of the pipe 9, which humidifies thegas injected into the pipe.

[0022] The humidifier 16 can comprise water, which can be heated to avariable, preset temperature. It is then possible to evaluate thesensitivity of the pharyngeal mucous to temperature as well.

[0023] The method can be made more sensitive by using a localanaesthetic, for example xylocaine, sprayed onto the pharyngeal mucoussituated facing the pipe 9, under visual observation through themouthpiece 1 or directly after the device has been removed. Thesensitivity is then re-evaluated after a minimum time delay enabling theanaesthetic to produce its effect, for example 5 minutes. Then othersprayings of the local anaesthetic can be administered onto thepharyngeal mucous using the same procedure in order to define aneffect-to-dose relationship.

[0024] Due to the heterogeneity of the sensitive innervation of thepharyngeal mucous, the sensitivity can be evaluated using the sameprocedure as that described above on zones other than that of thepalate, such as for example the pillar of fances, the rear wall of thepharynx or the nasopharynx.

[0025] Due to the heterogeneity of the chemical receptors(chemoreceptors) of the pharyngeal mucous, the gas flow can consist of aflow of air, oxygen or carbon dioxide in order to evaluate therespective part played by the different types of receptors in senseperception of the pharyngeal mucous and their involvement in pathologiesarising from malfunctioning of this perception.

[0026] In order to evaluate the different parts of the dilating reflexarc of the pharynx (afferent sensitive part and efferent motor part), itcan be envisaged to combine sensitive evaluation, as has been describedabove, with evaluation of the motor response, such as appreciation ofthe electromyographic activity of a pharynx dilating muscle, for examplethe genioglossus muscle, in particular in response to a negativepressure applied to the upper respiratory tract.

[0027] In order to eliminate the subjective nature of the subject'sresponses, or to avoid non-understanding of the instructions or toovercome a lack of co-operation, it can be envisaged to combineevaluation of sensitivity with recording of somesthetic evokedpotentials. A sufficiently high air flow to trigger a sensitivestimulation, for example 2 L/min, then has to be fixed, and this gasflow be administered in brief and intermittent manner at a givenfrequency and for a sufficient time for it to evoke anelectro-encephalographic cortical response (evoked potential) that isable to be averaged.

1. A mouthpiece intended for a device designed for evaluating the sensitivity of the pharynx, characterized in that it comprises an open mouthpiece (1) having internal dimensions enabling visual inspection of the pharynx, a thin guide tube (2) fixed along an internal wall of the mouthpiece (1) and comprising a first articulated end (3) salient from a first end of the mouthpiece, a pipe (9) designed to be connected via a first end to a compressed gas source and inserted via a second end inside the guide tube (2), and means (14) for fixing the pipe in the guide tube in a pre-determined position.
 2. Mouthpiece according to claim 1, characterized in that the pipe (9) comprises a measurement scale (11).
 3. Mouthpiece according to one of the claims 1 and 2, characterized in that the mouthpiece (1) is cylindrical.
 4. Mouthpiece according to any one of the claims 1 to 3, characterized in that the mouthpiece (1) comprises an external holding rim (6) at its first end.
 5. Mouthpiece according to claim 4, characterized in that the mouthpiece (1) comprises a holding rib (7).
 6. Device for evaluating the sensitivity of the pharynx, comprising a compressed gas source and means for blowing gas in the direction of the pharynx, characterized in that it comprises a mouthpiece according to any one of the foregoing claims and means (15) for measuring the flow rate of a gas injected into the first end of the pipe (9).
 7. Device according to claim 6, characterized in that the gas is air.
 8. Device according to claim 6, characterized in that the gas is oxygen.
 9. Device according to claim 6, characterized in that the gas is carbon dioxide.
 10. Device according to any one of the claims 6 to 9, characterized in that it comprises humidifying means (16) to humidify the air injected into the pipe.
 11. Device according to claim 10, characterized in that the humidifying means (16) comprise water heated to a variable preset temperature. 